The present invention relates to apparatuses and methods for wind turbines, and, more particularly to the use of discretely variable ratio gear boxes in wind turbines.
Older wind turbines are of the fixed speed and fixed pitch variety. Their efficiency is never optimized because wind speeds vary and wind input varies. Newer wind turbines are of the variable speed and variable pitch variety. They have a variable output from the gear box which creates a variable frequency and voltage from the generator. Then, in order to be coupled directly to the constant frequency and voltage of the electric grid, these wind turbines employ power electronics, i.e. a converter, to convert the variable frequency and voltage of the generator to the constant frequency and voltage of the electric grid. This power electronics is (i) very expensive, (ii) of heavy weight, (iii) unreliable and (iv) creates additional losses. There is a compelling need to have an apparatus and method that will improve the reliability and energy efficiency of wind turbines while providing wind turbines at the exact conditions demanded by electric grids and at reasonable cost.